SEOUL - South Korean President Lee Myung-bak said Tuesday Japan's Emperor Akihito should sincerely apologize for the country's colonial occupation of the Korean Peninsula if he intends to visit South Korea.

The Japanese monarch should offer a heartfelt apology to "those who died for independence" from Japan's 1910-45 colonial rule if he wants to visit South Korea, Lee said during a meeting with a group of teachers, according to his office Cheong Wa Dae.

"(The emperor) doesn't need to make a visit if he is to agonize for months over the wording and end up with the word "regrets"," Lee said, referring to the controversial 1990 remark by Akihito.

In 2010, the president invited the Japanese emperor to South Korea in a gesture of reconciliation marking the 100th anniversary of Japan's forcible annexation of the Korean Peninsula. Japan did not make an official response.

Tuesday's remark, which came a day before South Korea celebrates the 67th anniversary of its liberation from Japan, highlights markedly sour relations between the two Asian neighbors.

It could further raise diplomatic tensions brewing after Lee's high-profile visit last week to a set of East Sea islets claimed by both countries.

The one-day trip to the South Korean-controlled islets, known as Dokdo here and Takeshima in Japan, prompted Japan to summon its envoy from Seoul in protest.

Lying equidistant between the two neighbors, the sparsely inhabited islands have been a chronic source of diplomatic row.

South Korea, which regained its control of the islets following the end of the Japanese occupation, sees the recurring territorial disputes as a sign of an unrepentant Japan.